F 106 AB is the factory code describing the car as
a carburetted 308 Berlinetta, followed by the individual serial number of
the car.

The first serial number given to a 308 GTB is 18677.
Before the start of production, there were three prototypes (18317, 18319,
18321). The last fiberglass car is, according to most of the books, s/n
21289. The first steel-bodied car is regarded to be 20805. But there is
at least one steel car known in the USA with a lower number, having definitely
a steel body! Experts claim that all 308 GTB's destined for the US market
with numbers higher than 20000 are steel cars. And most of the literature
says that the last carburetted 308 GTB built in 1980 was s/n 34349. Ferrari once had published a table on the Ferrari Owners Website, in which 34329 is mentioned as the last one. But
according to the Servizio Assistenza Tecnica of Ferrari, even after 34349 there
were manufactured another five: 34377 - 34379 - 34389 - 34465 - 34503!

Compiling Ferrari serial numbers and researching
the histories of the respective cars has become a fascinating hobby for
many enthusiasts around the world. For some Ferrari experts it is also a
vital part of their profession.

Here is a list of the approximately 1,700 chassis numbers currently in my database: